Biologists say the more food deer can gobble before heavy snow arrives, the better chance they have to survive a harsh winter

Deer don’t as a rule eat candy bars, although of course confectioners don’t add bitterbrush or fescue to their sweet concoctions either.

Candy bars do, however, serve as a useful analogy for biologist Leonard Erickson as he talks about the benefits to deer herds of the recent spell of warm and occasionally damp weather that has invigorated the growth of grass in parts of Northeastern Oregon.

For deer, that lush new growth is the caloric equivalent of the candy bars that a hiker or a hunter might toss in a backpack to stave off hunger pangs during a hard day in the mountains, said Erickson, who works at the Oregon Department of Fish and Wildlife (ODFW) office in La Grande.

“That grass is the food that helps deer store fat to get through the winter,” Erickson said.

Once the snow comes and the temperatures plummet, deer will have to rely on less nutritious forage. At the same time, they’ll need to burn more calories just to maintain their body temperature during the region’s sometimes frigid periods.

The more fat the animals can accumulate during the autumn, the longer they can withstand winter’s deprivations.

This fall’s greenup started a few weeks later than in 2016, and Erickson said the amount of quality forage is lower than a year ago.

“But it’s getting better,” he said on Tuesday.

Erickson’s ODFW colleagues elsewhere in the region agree with his assessment.

“We are starting to see some greenup at the mid to lower elevations,” said Pat Matthews, biologist at ODFW’s Enterprise office, which manages deer herds in Wallowa County. “There’s not a lot, but it’s certainly there.”

The situation was quite different just a month ago, said Brian Ratliff, district biologist at the agency’s Baker City office.

At the start of November, following a summer and early fall that were drier than average, green forage was scarce in most places, Ratliff said.

And significant amounts of snow fell in the mountains in mid-October, making it even harder for deer to amass those critical fat reserves.

But starting around the middle of November the weather pattern shifted, bringing balmy temperatures and occasional rain.

The high temperature at the Baker City Airport, for instance, was above average on 21 straight days, from Nov. 9-29.

The mild weather is a boon for deer, Ratliff said, because they can store more of the food they eat as fat rather than immediately turning the calories into body heat.

“So far we’re doing well,” he said. “A lot of times by Thanskgiving we have snow at the lower and middle elevations, but right now we’re virtually snow-free.”

Matthews agreed.

“Every day that goes by that you don’t have snow on the ground it’s a benefit,” he said.

The late flush of green grass helps upland game birds as well, which also eat the new growth.

All three biologists temper their optimism by pointing out that no matter how healthy deer might be now, conditions over the next three to four months will decide the herds’ fate.

A harsh winter, with deep snow and prolonged polar temperatures, can wreak havoc even on animals that were plump at the start of the season.

You need look back only one year to find a textbook example of this phenomenon.

In the fall of 2016 there was a similar stretch of benevolent weather, though it happened in the first half of November rather than the second.

But even so, biologists cautioned then that the abundant forage only improved the odds that deer would survive the winter — there were no guarantees.

As it turned out, the winter of 2016-17 was the most severe in 24 years in much of the region.

Thousands of deer died, with losses heavier in Baker County and parts of Union County.

Populations dropped so much in some areas that ODFW cut in half the number of buck hunting tags for Baker County’s four units this fall, and by 35 percent in some Union County units.

The situation on the cusp of this winter is slightly different, the biologists said.

Although this autumn’s greenup wasn’t as widespread as in 2016, deer were generally in better condition this year because the drought is over. In 2016, by contrast, the dry spell was ongoing, and forage was lacking in parts of the region during the summer. That wasn’t the case in 2017.

In addition, the later arrival of the greenup this fall could give bucks an advantage they didn’t have in 2016.

November is the mating season for deer — the rut, as it’s known colloquially — and during those weeks bucks are so dedicated in their pursuit of does that they all but forget to eat and tend to lose fat reserves rather than add to them.

That’s the main reason that a larger percentage of bucks than does usually dies during harsh winters — the bucks are comparatively skinny just when the worst weather commences.

But this year, with green forage still available as the rut is nearly over, bucks will have a chance to replenish some of the fat they shed over the past month.

Or as Erickson puts it, “when they start thinking about grass again instead of girls.”